Method of improving the wrinkle recovery of acrylic fabrics



3,395,037 METHOD OF IMPROVING THE WRINKLE RECOVERY OF ACRYLIC FABRICS Julian .I. ll-Iirshfeld and Bertie J. Reuben, Decatur, Ala.,

assignors to Monsanto Company, St. Louis, M0., a corporation of Delaware No Drawing. Filed Dec. 28, 1964, Ser. No. 421,621

5 Qlaims. (Cl. 117139.4)

ABSTRACT OF THE DISCLOSURE Wrinkle recovery of fabrics of fibers comprising acrylonitrile polymers, or so-called acrylic fibers, is substantially improved by subjecting the fabric to the action of an aqueous solution of hydrogen peroxide at elevated temperatures, and thereafter causing the heat setting of the fabric.

This invention relates to an improved method of increasing the wrinkle recovery of fabrics of fibers comprising acrylonitrile polymers, or so-called acrylic fibers. The term acrylonitrile polymers as used throughout the instant specification and claims is intended to include copolymers, ter-polymers, and blends thereof, said polymers containing at least 80 percent by weight of polymerized or copolymerized acrylonitrile in the polymer molecule and correspondingly up to about percent by weight of other ethylenically unsaturated monomers copolymerizable therewith.

Fabrics of acrylic fibers are known to be somewhat deficient in their ability to recover from creasing or wrinkling. The ability of a garment to shed wrinkles after being worn is an important factor in determining the general usefulness of a fabric for garment manufacture and the consumer acceptance of the garments themselves. Accordingly, the relatively poor wrinkle-shedding ability of fabrics of acrylic fibers or of fabrics containing such fibers blended with other fibers, such as wool, has imposed some limitation on the use of these materials in clothing manufacture.

It is known that heat-setting of acrylic fabrics is effective to impart to such fibers a degree of wrinkle recovery capability. The method is generally described by A. D. Rosenberg in the Journal of the Textile Institute, vol. 54, No. 7, July 1963, pp. 146155. As shown therein, the ability of a fabric containing an acrylic fiber component to recover after creasing or wrinkling is enhanced by subjecting the fabric to a hot air treatment at about 383392 F. for a period of up to about seconds. The ease and simplicity of this heat-setting operation renders it of great value in the processing of acrylic fabrics. Nevertheless, because of the importance of the problem of wrinkling, it is obviously desirable to provide a means of increasing the effectiveness of the heat-setting method.

It is therefore, the principal object of this invention to provide a means whereby the ability of fabrics comprising acrylic yarns to recover from creasing or wrinkling is enhanced. It is an additional object of the invention to provide a means of rendering such fabrics more suitable for use in the fabrication of garments. It is a more specific object to render heat-setting of acrylic fabrics more effective for its intended purpose. The means of attaining these and certain related objects Will be apparent from the description following.

In general, the objects of the invention are accomplished by the expedient of subjecting an acrylic fabric, prior to heat-setting, to a pretreatment which, of itself, is ineffective to increase the wrinkle recovery of the States Patent 0 "ice 3,395,037 Patented July 30, 1968 fabric but which, in conjunction with subsequent heatsetting, yields a fabric of unexpectedly much lower wrinkle retention than that afforded by heat setting alone.

The above-mentioned pre-treatment involves subjecting the acrylic fabric or other acrylic textile article to the action of an aqueous solution of hydrogen peroxide at a somewhat elevated temperature for a period of time which, depending on the temperature of the treating solution and the concentration of the hydrogen peroxide contained therein, may vary from about 15 seconds to about 2 hours. After the thus described treatment, the fabric may be dried or it may be carried wet to additional processing steps, such as scouring, dyeing and the like, preferably after rinsing to remove residual hydrogen peroxide. The fabric is, of course, preferably finally dried before being subjected to the heat-setting operation.

Heat setting is accomplished by heating the fabric at a temperature of from about 250 F. to about 450 F., while maintaining substantially unchanged the original dimensions of the fabric. Depending on the temperature employed, heating of the fabric is continued for from about 5 seconds to about 15 minutes. Choice of temperature and duration of treatment is a matter within the skill of the art.

The concentration of hydrogen peroxide in the treating bath is not critical. As a practical matter, the aqueous bath should contain from about 1.0 percent to about 60 percent by weight of hydrogen peroxide, an amount equal to 10 percent being generally preferred. The bath may be maintained at a temperature of from at least F. to about 212 F. Advantageously, however, a minimum temperature of about F. will be maintained. The duration of contact between the hot aqueous hydrogen peroxide solution and the acrylic fabric will, of course, depend broadly on the temperature of the solution and its concentration. In practice, however, a treatment time of from about 10 minutes to about 2 hours will ordinarily be employed in an exhaust operation. Nevertheless, no difficulty will be encountered should the fabric be allowed to remain in the hydrogen peroxide solution for periods longer than the practical maximum time.

It is, of course, possible to shorten the duration of the treatment with the hydrogen peroxide solution by heating the impregnated textile article under pressure greater than atmospheric, thereby to achieve a temperature higher than that possible with an open bath. Thus, the same effect can be obtained by treatment for about 15 seconds at about 350 F. or by treatment for 10 minutes at 212 F. Because of this, continuous treatment becomes feasible. For example, a fabric may be continuously impregnated with aqueous hydrogen peroxide by padding, then passed into and through a chamber containing saturated steam at a pressure significantly greater than atmospheric.

While the pH value of the treating solution is not a critical consideration, a mildly acidic bath, that is, one exhibiting a pH value of from about 5 to less than about 7, is generally preferred.

While it will ordinarily be found most convenient to carry out the pro-treatment on the acrylic fabric itself, it is within the scope of the invention to treat acrylic textile articles other than the fabric, thereafter to form the fabric from the thus pre-treated textile article and finally to subject the fabric to the heat-setting operation. Accordingly, the fibrous acrylic textile article may be in the form of spun yarn, monofilament, staple or the like. This method of carrying out the invention has particular application if it is desired that the final fabric contain a component other than the acrylic component, which other component is preferably not to be exposed to the action of hydrogen peroxide.

The method of the present invention is applicable to textile articles of all acrylic fibers which are formed from polymers containing at least 80 percent by weight of acrylonitrile in polymeric form. These include fibers formed from polyacrylonitrile, copolyrners, and terpolymers containing at least 80 percent of acrylonitrile plus one or more mono-olefinic monomers copolymerizable therewith, and blended polymers and copolymers in which the blend composition contains at least 80 percent acrylonitrile. The blended polymers, for example, may comprise a major amount of a polymer of somewhat more than 80 percent acrylonitrile and a minor amount of another polymer or copolymer, the polymers being so proportioned that the blended polymer contains at least 80 percent acrylonitri'le by weight.

The copolymers and terpolymers of at least 80 percent acrylonitrile may contain copolymerized therewith such other mono-olefinic monomers as acrylic haloacrylic, and methacrylic acids; esters such as methyl, butyl, octyl, methoxymethyl, and chloroethyl methacrylates and the corresponding esters of acrylic and haloacrylic acids; methacrylonitrile; vinyl and vinylidene halides such as methacrylonitrile; vinyl and vinylidene halides such as vinyl chloride, vinyl fluoride, vinylidene chloride, l-fiuorol-chloroethylene; vinyl carboxylates such as vinyl acetate,

vinyl chloroacetate, vinyl propionate, and vinyl stearate; N-vinylimides such as N-vinylphthalimide, and N-vinylsuccinimde, N-vinyllactams such as N-viny-lcaprolactam and N-vinylbutyrolactam; aryl compounds such as styrene and vinyl naphthalene, and other compounds such as methyl vinyl ketone, methyl fumarate, methyl vinylsulfone, fumaronitrile, maleic anhydride, the vinyl pyridines such as Z-VinyIpyyridine, and 4-vinylpyridine, the vinylsubstituted alkyl pyridines, such as 4-ethyl-2-vinylpyridine, 5-ethyl-2-vinylpyridine, and 2-methyl-5-vinylpyridine; the isomeric vinylpyrazines, the various isomeric vinylquinolines, the vinylimidazoles and the vinyl-benzoxazoles.

The invention will be more fully described in the following examples which are given by way of illustration only.

Example I The fabric employed in this and the following examples had the following construction:

Ends/inch 60.

Picks/inch 48.

Wt./sq. yd. 5.3 oz.

Warp count 32.3/2.

Filling count 32.6/2. Twist/inch, warp Ply 5 S. Twist/inch, filling Ply 5 S. Twist/inch, warp Shingles 1 Z. Twist/inch, filling Shingles 1 Z.

The material of which the yarn was made was a copolymer containing, in copolymerized combination, about 94 percent of acrylonitrile and about 6 percent of vinyl acetate.

The fabric was first thoroughly scoured in an alkaline scouring bath, rinsed and dried. Four sample sections measuring 8" x 12" were taken from this scoured material. Two of these samples were immersed for 90 minutes in a bath containing percent by volume of a percent solution of hydrogen peroxide in water; the pH of this solution was adjusted to a value of 6.4 and its temperature was maintained at 195 F. At the end of 90 minutes the samples were thoroughly rinsed and dried.

All four samples were then blank dyed in an alkaline bath in known manner, rinsed and dried.

One of the hydrogen peroxide treated samples and one which had not been so treated were mounted on pin frames to hold the samples dimensionally stable and were then placed in an oven, the temperature of which was maintained at 428 F., for 25 seconds. Thereafter all four samples were again scoured, rinsed, dried, lightly pressed on a Hoffman Press to remove wrinkles and finally conditioned at 65% R.H.i2% RH. and 70 F.i2 F. The samples were identified as follows:

TABLE L-ANGLE RECOVERY, WRINKLE RECOVERY TEST A B C D Warp Fill Warp Fill Warp Fill Warp Fill Averages. 128 124. 7 128. 3 126. 7 134. 7 132. 7 139. 7 136. 7

The larger the value of angle recovery the more efiicient is the fabric in question in regard to its ability to recover after creasing and wrinkling. Accordingly, it is immediately evident that treatment with hydrogen peroxide alone (B) is essentially without effect on this property of acrylic fabric but that its use in conjunction with heatsetting (C), which significantly improves the fabric in this respect, markedly enhances the elfect of the latter (D). That is, the combination of hydrogen-peroxide treatment with heat setting leads to an angle recovery 9.1 percent greater than that of the blank in the warp direction and 9.6 percent greater in the fill direction; the corresponding values given by heat setting alone are 5.2 percent and 6.4 percent respectively.

Example II The relative permanence of the effect produced by the method of the present invention was determined by subjecting a sample corresponding to (D) above to both repeated standard launderings and to repeated standard dry cleanings. The laundering method employed was that described in American Association of Textile Chemists and Colorists Text Method 88-l960T, Test 3, scale from 1 to 5 and the dry cleaning methods is that described in American Standards Association No. L14.l201961 (AATCC Technical Manual, Part II B-SS). After three such dry cleaning operations the sample displaying a retention value of 3 was obtained.

Inasmuch as many widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it will be understood that the invention is not to be limited to the specific embodiments thereof except as defined in the appended claims.

We claim:

1. A method for improving the wrinkle recovery of a fabric comprising yarns of an acrylic polymer which contains at least about percent by weight of acrylonitrile in the polymer molecule comprising the steps of subjecting said fabric to the action of an aqueous solution of hydrogen peroxide and thereafter causing the heat setting of said fabric.

2. A method for improving the wrinkle recovery of a fabric comprising yarns of an acrylic polymer which contains at least about 80 percent by weight of acrylonitrile in the polymer molecule comprising the steps of impregnating said fabric with an aqueous solution containing from about 1 percent to about 60 percent by weight of hydrogen peroxide and maintained at a temperature of from about 70 F. to about 350 F., maintaining impregnating contact between said fabric and said solution for from about 15 seconds to about 2 hours and thereafter causing the heat setting of said fabric.

3. A method for improving the wrinkle recovery of a fabric comprising yarns of an acrylic polymer which contains at least about 80 percent by weight of acrylonitrile in the polymer molecule comprising the steps of impregnating said fabric with an aqueous solution containing from about 1 percent to about 60 percent by weight of hydrogen peroxide and maintained at a temperature of from about 70 F. to about 350 F., maintaining impregnating contact between said fabric and said solution for from about 15 seconds to about 2 hours and thereafter raising said fabric to a temperature of from about 250 F. to about 450 F. for a period of from about 5 seconds to about 15 minutes while maintaining substantially unchanged the original dimensions of the said fabric.

4. A method of producing a fabric of improved wrinkle recovery and comprising yarns of an acrylic polymer which contains at least about 80 percent by weight of acrylonitrile in the polymer molecule comprising the steps of impregnating the said yarns with an aqueous solution containing from about 1 percent to about 60 percent by Weight of hydrogen peroxide and maintained at a temperature of from about 70 F. to about 350 F., maintaining impregnating contact between said yarns and said solution for from about 15 seconds to about 2 hours, embodying the thus treated yarns in a fabric and thereafter raising the said fabric to a temperature of from about 250 F. to about 450 F. for a period of from about 5 seconds to about 15 minutes while maintaining substantially unchanged the original dimensions of the said fabric.

5. A method of producing a fabric of improved wrinkle recovery and comprising yarns of an acrylic polymer which contains at least about 80 percent by weight of acrylonitrile in the polymer molecule comprising the steps of impregnating a fibrous form of said polymer with an aqueous solution containing from about 1 percent to about percent by weight of hydrogen peroxide and maintained at a temperature of from about F. to about 350 F., maintaining impregnating contact between said fibrous form of said polymer for from about 15 seconds to about 2 hours, embodying the thus treated fibrous form of said polymer in a yarn, embodying the v References Cited FOREIGN PATENTS 3/1949 Australia. 7/1948 Great Britain.

OTHER REFERENCES British Rayon and Silk Journal, A. J. Hall, September 194-9 (page 72, pertinent).

WILLIAM D. MARTIN, Primary Examiner.

T. G. DAVIS, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N0. 3 ,395 ,037 July 30 1968 Julian J. Hirshfeld et a1.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 61, "displaying" should read displayed Column 6, line 19, "rinsing" should read raising Signed and sealed this 31st day of March 1970.

(SEAL) Auest:

Edward M. Fletcl ier, Jr.

Commissioner of Patents Attesting Officer WILLIAM E. SCHUYLER, JR. 

